Abrasive article



- March 1945- c. F. KEELERIC ABRASIVE ARTICLES Filed May 11, 1944 yVENTOR QI fA I Mm; 3 BY 7 )ilmc JRJK .I

AITORNEY Patented Mar. 6,1945

UNITED STATES PATENT OFFICE ABRASIVE ARTICLE George F. Keelerlc, Washington, D. 0.

Application May 11, 1944, Serial No. 535,149

Claims.

- tageously be made.

Abrasive tools are now frequently made in the form of wheels of largediameter. To reduce the weight of the wheel, it is preferable to make the body of a light material, such as a suitable plastic, although a body made of alight metal or alloy by sintering or by die casting 'may also be used.

Such a body may be secured to the rim by m'olding with heat and pressure to form the body in direct contact with the rim. As the rim is formed of a bonding metal of a coeflicient of expansion different from that of the material of which the body is made, the body is likely to shrink somewhat from the rim when it cools after molding.

The present invention is, accordingly, directed to the provision of an abrasive tool in which provision is made for interlocking the layer or rim carrying theabrasive particles to the tool body to prevent separation of the parts. In the tool of the invention, the objective is attained by forming the layer with one or more integral extensions, which enter'the molded or cast body and iiglutde offset portions which provide the locking e ec In making such a tool by the new method, the

Figures 2, 3 and 4 are sectional views of a blank used in making the wheel of Figure 1, the views showing different steps in the use of the blank;

Figure 5 is a sectional view through an electrolytic cell showing a stack of the blanks ready for the plating operation;

Figure 6 is a sectional view of one of the blanks, shown in Figure 5, after the completion of the plating operation; and

Figure 7 is a sectional view showing the manner of forming the body of the tool of Figure l.

The tool shown inFigure 1 is a grinding wheel of the peripheral type, that is, one in which the abrasive material is on the peripheral surfaces, and the tool includes a layer or rim ID of a bonding'metal, such as iron in which a superficial layer of abrasive particles I I is mounted. 'In the drawing, the particles have been shown much exaggerated in sizefor purposes of illustration,

layer of bonding metal is formed by electrodepositlon and, in this operation, the deposit is controlled to produce the extensions referred to. The layer is thus built up to the desired thickness and the extensions formed in a single. operation and the extensions are integral with the layer.

In the new tools, the abrasive particles may take the form of a single superficial layer on the surface of the bonding metal or they may be distributed throughout the bonding metal. When diamond particles are used as the abrasive, a thin su erficial layer of such particles on the workin surface of the tool is satisfactory, and, for purposes of explanation, a tool which includes a single layer of diamonds will be illustrated and described in detail. It will be apparent, however. that the utility of the invention is not limited to the use of that specific abrasive or to the employment of a single layer of abrasive particles.

For a better understanding 0! the invention.

but it is to be understood that they will vary greatly in size, depending upon the use to which the tool is to be put. When the abrasive is formed of diamond particles, these particles may vary through a wide range of size, as, for example, from 80 to 600 mesh.

The rim ID of the tool is mounted on, a tool body l2, which is formed with a central opening surface of the rim. These extensions have in-- wardly offset end portions or ribs l5 so that the distance between the offset portions is less than the thickness of the tool body. In the formation of the tool body, the extensions lie within the body and thus form and fill cavities in the body. Because of their oilset portions, the extensions provide a dovetail connection between the rim that of forming the rim and, for this purpose, a

blank I8 is employed. The blank is preferably made-oi hardened steel and it is annular in form ring 22 in place is then mounted on the internal and has an inner surface I I of the shape and size .of the rim to be produced. The blank is provided with a circumferential channel I8 in its upper face and a rib I9 of corresponding shape in its lower face so that the blank may be stacked o with others without danger of side slip.

In the use of the blank, its surface I1 is provided with a coating of a suitable soft material which may, for example, be a thin film 20 of lead applied by electrodeposition. Instead, a thin coating of an adhesive may be applied to the surface ll of the blank, if desired, but the lead is preferable because it is electroconductive. After the application of the film to the inner surface of the blank, the abrasive particles II are disl tributed over the film and forced into it in any suitable manner. Preferably, the particles are rolled into the film and sufllcient pressure is applied to force them through the film and into contact with the surface of the blank. After the desired quantity of particles has been so embedded in the blank, a number of similar blanks are prepared.

When the blanks are ready, a ring 2| of thin metallic material, such as tinfoil, is applied to each face of'each blank, the ring having an innerdiameter such that the ring-projects into. the

opening through the blank to terminate inward from the film 20 in which the particles are embedded. The amount by which the rings 2| project inward from'the inner wall of the blank depends on the length that the projections from the rim are to have. The length of the projections is determined by'the thickness of the bonding layer and the strength of the'interlock that is desired. In a typical case, the inner diameter of the rings 2| will be about 4 mm. less than that of the blank;

After the rings 2| have been placed in position, the blanks are to be assembled one above another in the form of a stack within an electrolytic cell. Preliminarily, however, a ring 22 of insulating material is placed against the under surface of the blank which is to form a bottom element of. the stack, the ring 22 having an inner diameter slightly less than that of the ring 2| of foil with which it lies in contact. The blank |8a with the flange 23 of a ring of insulating material 24, which may be supported in the cell in any suitable manner, as,- for example, on brackets 25. With the blank in this position, a ring 22a of insulating material, similar to ring 22, is placed upon the ring 2| of foil on the upper surface of the blank. A ring 24a, similar to ring 24, is then placed upon the upper edge of ring 24, with the internal flange of ring24a overlying blank lid. The next blank lib is placed in position on the internal flange of ring 24a and the various parts are assembled as described to build up a stack 6 of blanks of any suitable number. Each blank carries a thin film of metal in which the abtasive particles are embedded on its inner surface. and each blank also has rings of thin metallic material applied to its upper and lower faces with the rings overhanging the inner surface of the blank. The rings 2| are held in place by rings of insulating material 22 and the insulating rings separate the conductive rings 2| on adjacent. blanks.

When the stack has been assembled within the cell, as described, a connection 23 is made to one of the blanks of the group and the electrolyte 21 is then introduced into the cell to a level which will cover the stack. The anode 23 is then in- 7 viously described. As each blank is provided with a ring 2| at both top and bottom, the layer of deposited metalis formed with two integral extensions l4 and,*as these extensions are built up. the metal is so deposited as to form the offset portions I5 extending inwardly from the extensions and toward one another.

When the electrodeposition has been carried on to produce a layer ll) of the desired thickness on each blank, the stack is removed from the cell and the rings 22 and 24 are separated therefrom.

The rings 2| may also be removed, if desired, but since these rings are of light foil, it is immaterial whether'they are removed or not. The rim carrying the abrasive particles, which has been formed on the inner surface of each blank may then be. aflixed to a tool body, and the body is preferably formed while the rim remains in place on the blank. When this is done, the blank supports the rim during the formation of the body and distortion of the rim is prevented.

The formation of the body within therim carried by the blank may be performed in various ways and the molding of a body of plastic material is illustrated in Figure 7. For this operation. the blank i6 is mounted on a plate 29 having a channel to receive the rib i9 on the .under surface of the blank. The mold cavity is then completed by an annular block 39, which is placed on top of the blank l6 and is formed with a rib 3|, which enters the channel l8 in the upper surface of the blank. The plate 29 may be provided with a pin 32 of the diameter of the opening l3 to be formed through the tool body and extending upwardly from plate 29 a substantial distance.

When the mold cavity has been assembled as described a quantity of plastic material 33 is introduced into it and a plug 34 is then inserted in the opening through the annular block 39 to rest upon the plastic material. The'plug has an opening 35 to receive the pin 32 and it is also provided with a passage 39 extending through it and into which excess plastic material may be forced.

When the mold has been filled and the plug 34 placed in position, the assembly is placed in pressure are thereby applied to the plastic material 33 to compact and form it into the solid tool body l2. In the molding operation, the'plastic material is forced into the space between the integral extensions l4 and the extensions form and fill cavities within the tool body. When the molding operation is completed, the tool body is molded with a dovetail connection to the rim carrying the abrasive particles, After the molding operation, the mold parts may be disassembled and the tool body removed from the blank in any suitable manner. finishing operations, the tool is in condition for use.

Instead of forming the body of plastic material by molding, the body may be made of light metals or alloys by die casting or by powder metallurgy. Such operations are well known and require no further description.

I claim:

After suitable 1. A method of making an abrasive tool, which comprises mounting abrasive particles on a support, electrodepositing metal over the particles and controlling the electro-deposition to build up a deposited layer which overlies the particles and is provided with an integral extension of deposited metal, said extension projecting from the face of the deposited layer opposite to that in which the particles lie, and afllxing a tool body to the layer with the extension entering a cavity in the body.

2. A method of making an abrasive tool which comprises mounting abrasive particles on a support, mounting a conductive member on the support with a portion thereof projecting beyond the particles in the direction in which the particles extend from the support, electro-depositing metal over the particles and onto the projecting portion of the member to form a layer having an integral extension. along the side of the said portion adjacent the particles of such length as to extend beyond the particles, and afllxing a tool body to the layer with the extension engaging with the body.

3. A method of making an abrasive tool which comprises mounting abrasive particles on a support, mounting conductive members on the support at opposite sides of the area on which the particles are mounted with portions of said members projecting beyond the particles in the direction in which the particles extend from the support, electrodepositing metal over the particles and onto the inner sides of the projecting portions of the members to form a layer having integral extensions with thickened free end portions extending beyond the metal deposited onto the particles, and affixing a tool body to the layer with the extensions interlocking the body to the layer. a

4. A method of making an abrasive tool which comprises mounting abrasive particles on a support, stacking a plurality of supports one upon another with conductive members between them, portions of said members projecting beyond the particles in the direction in which the particles extend from the supports, electrodepositing metal over the particles and onto the projecting portions of the members to form a layer on each support having integral extensions with thickened free end portions along the sides of therespective projecting portions adjacent the particlesof such length as to extend beyond the particles, and ailixing, a tool body to each layer with the extensions therefrom engaging the body and interlocking it to the layer.

5. A method of making an abrasive tool which comprises mounting abrasive'particleson a support, mounting conductive members on the support at opposite sides of the area on which the particles are mounted with portions of the members projecting beyond the particles in the direction in which the particles extend from the sup- .port, electrodepositing metal over the particles 

